Learning Objectives.

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April Scott
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1 Learning Objectives 1. Describe the Functions/Components/Deficits of the motor system (table) 2. Explain the difference between upper and lower motoneurons 3. Describe the roles of the Basal Ganglia and Cerebellum in control of movement Christopher Cohan, Ph.D. Dept. of Pathology/Anat Sci Jacobs School of Medicine

This allows us to attend to many other tasks while we move. Reflexes are unlearned, automatic responses.

2 From Sensation To Movement What is Different about Movement Sensory systems require constant attention for perception. Movement is automatic. It is learned and then it occurs without need for conscious control. This allows us to attend to many other tasks while we move. Reflexes are unlearned, automatic responses. In the spinal cord, they depend upon local circuits formed developmentally and do not require the brain (eg withdrawal, postural adjustment, deep tendon reflex). Clinical tools!

3 What s Involved in Movement Motor system is much more complex than sensory system: Multiple components and pathways involved Each pathway has complex features Each pathway controls a specific aspect of movement These pathways act simultaneously during a movement

uphill, downhill, fast, slow Sensory feedback Speed, direction, amplitude, force

4 What s Involved in Movement Plan - what s moving (eg GPS) Start - get it going from rest (eg car starter) Move - some rhythmic (eg car engine) Adjust/Coordinate uphill, downhill, fast, slow Sensory feedback Speed, direction, amplitude, force Maintain balance/posture don t fall It all happens simultaneously and without much thought

5 Movement Control FUNCTION COMPONENT DEFICITS Start Basal Ganglia Spontaneous movement Move (Plan) Understanding the type of deficit is KEY to identifying the motor component involved in lesion. Upper/Lower Motoneurons Weak/Paralyzed Plan Cerebellum Ataxia (jerky) Adjust Cerebellum Ataxia/Inaccurate Coordination uncoordinated Balance Cerebellum Falling/Nystagmus. Download the Template for Motor Systems to help organize this information.

6 How We Move 1. Perform the movement Like the ENGINE of your car cortical motor area One on each side

7 How We Move Signals for movement travel from: 1. Brain to spinal cord 2. Spinal cord to muscles

8 How We Move Involves 2 components with a relay (connection) in the spinal cord Brain (corticospinal tract) Spinal cord (spinal nerves) Muscles

9 How We Move upper motor neurons A 2 tier system: 1. Brain The Boss creates the plan and activates it 2. Spinal cord the employee just does what it s told to do lower motor neurons This distinction is important because it recognizes the different functions explains different symptoms when each component is damaged

10 How We Move upper motor neurons Serious consequences if damaged Weakness or NO movement lower motor neurons

11 UMN are not sufficient to control all the complex operations involved in movement. Two additional helpers are needed: basal ganglia cerebellum Their effect is simple - adjust UMN activity

12 1. Helps get things started: Basal Ganglia increases upper motoneuron activity (think of the starter motor on a car) idea action Consequences of damage (starter on car doesn t work or stuck on) Starting - difficult Stopping - never

13 How We Move Adjust/Coordinate uphill, downhill, fast, slow Sensory feedback Adjust speed, direction, amplitude, force after the movement starts Maintain balance don t fall cerebellum

14 How We Move Adjust/Coordinate uphill, downhill, fast, slow Sensory feedback Adjust speed, direction, amplitude, force after the movement starts Maintain balance don t fall Consequences of damage - ATAXIA (loss of coordination) loss of accuracy, smoothness of movement, appropriate force, balance cerebellum

15 Upper/Lower Motoneurons Thalamus Cerebral Cortex Basal Ganglia Cerebellum corticobulbar head muscles LMN Brainstem UMN corticospinal body muscles Spinal Cord

16 Motor Components Helper #1 Cerebral Cortex Thalamus Basal Ganglia Cerebellum head muscles Brainstem body muscles Spinal Cord

17 Motor Components Helper #2 Cerebral Cortex Thalamus Basal Ganglia Cerebellum head muscles Brainstem body muscles Spinal Cord

18 Take-Home Message UMN/LMN perform the movement. Without that there is no movement. Other parts of the system build on that. The 2 helpers adjust UMN activity: Basal Ganglia start the movement Cerebellum coordinates the movement

Upper and Lower Motoneurons for the Head Objectives

Upper and Lower Motoneurons for the Head Objectives Know the locations of cranial nerve motor nuclei Describe the effects of motor cranial nerve lesions Describe how the corticobulbar tract innervates